Well it depends, there’s certainly an argument for like, the original CPU. I’m personally fine with emulation tbh, I do think someone maintaining the hardware is good for archival but I don’t have the space or funds for a bunch of the consoles I grew up with and either a CRT or expensive ass hdmi mods (which is another point of debate I suppose) but I like installing them for people and fixing old consoles is surprisingly lucrative, especially if you “Cadillac them up” with this stuff (assuming you can still find them cheap, which is incredibly difficult nowadays)

But changing the psu? That’s a no brainer. Functionality remains identical and the modern designs are superior because they simply couldn’t have existed 30+ years ago. Components have improved a lot in terms of efficiency since then and as a result the modern designs are much smaller and generate far less heat and ripple (two biggest factors for longevity). Using the original power supply just means stressing the motherboard more which is counterproductive if your goal is keeping the machine running as long as possible. The exception would be if you got a bad modern replacement, like if you designed your own poorly or pulled the trigger on an unknown one and did 0 testing. Repsx (and the associated other systems under the same name) are well designed and made.